Twenty-five people were killed and 69 others injured when two passenger buses collided head-on in central Pakistan.

The accident, which happened on a dangerous curve in Khanpur town in Rahim Yar Khan district on Monday, was probably caused by speeding, said police official Jamshid Shah.

Several children, college students and women were among the victims, Mr Shah said.

He added that police and rescue officials were using cutters to retrieve bodies trapped inside the two buses.

Dr Tasleem Kamran, at a government hospital where the injured were being treated, said nearly 40 of them were reported to be in a critical condition.

"We have declared an emergency. We desperately need blood," she said.

Local TV footage showed ambulances and rescue officials rushing the casualties to hospital.

Before the rescuers and police arrived, resident Waqar Ahmad said townspeople, who heard the sound of the crash, arrived at the scene and started pulling the victims out of the wreckage.

"We thought some bomb had exploded," he said.

Jamila Bibi, 60, was travelling in one of the buses, taking her nine-year-old son Faisal Ali to school.

The driver was reckless, she said. "We protested and asked him to slow down," she told the Associated Press from her hospital bed.

At one point, all the passengers stood up and asked the driver to slow down or stop, but he did not listen to anyone. Instead, she said, the driver told the passengers that anyone who was afraid could get off the vehicle.

Ms Bibi suffered minor injuries but said her son was badly injured and was fighting for his life.

Deadly road accidents are common in Pakistan, mainly because of bad road infrastructure and reckless driving.